There are a method in which a control subject connected to storage batteries with many-to-one relationship controls charge/discharge of the storage batteries collectively, and a method in which a control subject connected to a battery with one-to-one relationship controls a charge/discharge schedule of the battery.
When renewable energy large in output change is incorporated in an electric power system, it is useful that a battery system (energy storage) is utilized as a buffer because there is a possibility of a power failure accident if electric power is not transmitted stably. Battery systems are provided on a utility side which is a management region of a power producer and provided on a consumer side which is a management region of a home, a building, etc. in accordance with the scales so as to be utilized for the respective purposes. For example, as the purpose of use on the utility side of the power producer, a battery system is generally utilized for achieving a function called ancillary service by which the system is stabilized by adjusting the output at intervals of tens of seconds in accordance with instantaneous load change in order to keep the quality of electricity such as the frequency or voltage of the system. On the other hand, as the purpose of use on the consumer side such as a home, a building, etc., a battery system is utilized for achieving a function called peak shift by which low unit-cost nighttime electric power is stored to be flexibly used in a time zone of daytime having concentration of use of electric power. As to the relationship of control subject to battery system, there is assumed configuration of many-to-many relationship in which power producers perform charge/discharge control of battery systems provided on the consumer side under the condition that a predetermined incentive is given to the consumer side, in addition to configuration of one-to-one relationship in which operational limitation is provided by a power producer when the control subject is provided on the utility side or by a home or building administrator when the control subject is provided on the consumer side. For this reason, when there are plural control subjects for a battery system, rival for charge/discharge control occurs.
Because rival for charge/discharge control occurs when there are plural control subjects for a battery system, it is impossible to charge the battery beyond its capacity when, for example, contents of a new charge control instruction is applied in a situation that the battery system is executing charge control. On the other hand, when one single control subject is permitted to make charge/discharge control of the battery system for a divided period on a time axis, power throughput is lowered because the quantity of input/output per unit time of the battery cannot be utilized to the utmost. For this reason, according to the background art, it is difficult to increase the quantity of input/output power (power throughput) per unit time of each battery in a system in which battery systems and control subjects are connected to one another.